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2: Surgical Methods and Perioperative Care > Chapter 18 Surgical Haemostasis > Flashcards

Chapter 18 Surgical Haemostasis Flashcards

1
Q

What are the three main principles used to augment haemostasis?

A
  • Reduction in blood flow to affected area
  • Topical haemostatic agents
  • Antifibrinolytics
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2
Q

What are the three main principles used to augment haemostasis and list examples of each.

A
  • Reduction in blood flow to affected area
    • Topical vasoconstrictors
    • Hypotension/hypothermia/reduced perfusion
    • Distant control of blood flow
  • Topical haemostatic agents
    • Mechanical
    • Active
    • Haemostatic sealants
  • Antifibrinolytics
    • Serine protease inhibitor
    • Lysine analogues
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3
Q

What are the three main principles used to augment haemostasis, list broad examples of each, and specific examples

A
  • Reduction in blood flow to affected area
    • Topical vasoconstrictors
      • Epinephrine 0.01 - 1 mg/kg
    • Hypotension/hypothermia/reduced perfusion
    • Distant control of blood flow
      • Clamps or tourniquets
  • Topical haemostatic agents
    • Mechanical
      • Collagen
      • Gelatin
      • Cellulose
      • Polysaccharide spheres
      • Bone wax
      • Ostene
    • Active
      • Thrombin
      • Alginates
    • Haemostatic sealants
      • Fibrin
      • Synthetic sealants
  • Antifibrinolytics
    • Serine protease inhibitor
      • Aprotinin
    • Lysine analogues
      • TXA
      • Epsilon-aminocaproic acid
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4
Q

List vessels that can be permanently ligated (11 in total)

A
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5
Q

How long can the following vessels be ligated for?

Descending thoracic aorta

Pringle manouvre

Hepatic artery

Splenic artery and vein

Renal artery and vein

Abdominal aorta

A

5 - 10 mins: Descending thoracic aorta

10 - 15 mins: Pringle manouvre

30 mins: Hepatic artery

15 - 20 mins: Splenic artery and vein

30 mins: Renal artery and vein

30 mins: Abdominal aorta

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6
Q

How long can descending thoracic aorta be occluded for?

A

5 - 10 mins

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7
Q

How long can the pringle manouver be performed for

A

10 - 15 mins

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8
Q

How long can the hepatic artery be occluded for?

A

30 mins

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9
Q

How long can the renal artery and vein be occluded for

A

30 mins

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10
Q

How long can abdominal aorta be occluded for

A

30 mins

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11
Q

How long can splenic artery and vein be occluded for?

A

15 - 20 mins

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12
Q

What is an esmarch tourniquet

A

Esmarch tourniquets are usually made of a broad elastic material and are applied tightly from distal to proximal, thus exsanguinating the limb. The Esmarch bandage is then secured tightly at the proximal aspect of the limb, preventing blood from flowing into the limb during surgery; thus, the limb is not only prevented from bleeding but also has had the blood removed

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13
Q

What is the recommended pressure of a tourniquet?

A

100 mmHg above patients systolic BP

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14
Q

What is the formula for pressure exerted by a tourniquet

A

P is pressure (Pa)

T is bandage tension (N)

R is the radius of curvature of the limb (m)

W is bandage width (m).

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15
Q

What is recommended time limit for tourniquet

A

1.5 - 2 hours

(at which point muscle ATP stores are depleted)

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16
Q

Name 2 contraindications to (limb) exsanguination

A

Infection or neoplasia

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17
Q

What are the three categories of haemostatic agent

A
  • Mechanical
  • Active
  • Haemostatic sealant
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18
Q

List 5 possible complications of haemostatic agents

A
  • Exothermic reaction
  • Volumetric swelling
  • Immunogenic reaction
  • FB reaction
  • Inhibition of normal tissue healing
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19
Q

List 2 contraindications to use of haemostatic agents

A
  • Auto-transfusion (can pass through 40 um filter!) planned
  • Intravascularly
20
Q

How do mechanical haemostatic agents work?

A
  • Mechanical barrier –> tamponade
  • Scaffold for clot formation
21
Q

In vitro, which mechanical haemostatic agent performed best?

A

Microfibrillar collagen > collagen sponge > gelatin > cellulose

22
Q

What is source of gelatin?

A

Porcine

(“Gelofoam”)

23
Q

What mechanical and active haemostatic agents are often combined

A

Thrombin + gelatin

(N.B. Thrombin cant be combined with cellulose because cellulose –> acidic environment which inactivated thrombin)

24
Q

In terms of action, how does gelatin differ from cellolose

A

Gelatin doesnt cause platelet aggregation

25
Q

What type of collagen is used as haemostatic agent

A

Bovine type 2 collagen

(–> mechanical action but also enhances platelet aggregation)

26
Q

What is surgical

A

Oxidized regenerated cellulose

27
Q

Aside from haemostasis, name an additional feature of cellulose

A

Acidifying –> bactericidal

28
Q

What is a noteable feature of polysaccharide spheres?

A

500% volume expansion

Rapidly metabolised by endogenous amylases (24 - 48 hours)

29
Q

What is bone wax made of?

A

Beeswax + paraffin or isopropyl palmitate

30
Q

List 3 potential adverse effects of bonewax

A
  • Inhibits bone healing
  • Infection
  • Embolization
  • FB reaction

(not dog/cat studies though)

31
Q

What is Ostene

A

Mechanical haemostatic agent

Blend of water-soluble sythetic alkaline oxide co-polymers

Advantages:

  • No effect on bone healing
  • Little FB reaction
  • Less infection risk
  • Adheres better to wet bone surfaces
32
Q

What factor is thrombin

A

Factor 2

33
Q

How does thrombin work as an active haemostatic agent

A

Utilizes normal clotting cascade, actively converting fibrinogen to fibrin

i.e. ineffective of consumptive coagulopathy

34
Q

What is source of thrombin

What is a concern re repeated use of thrombin

A

Bovine, human or recombinant

Development of antibodies (which might cross-react with endogenous thrombin)

35
Q

What are alginates derived from

How do alginates –> haemostasis

A

Seaweed

Contact with saline/body fluids –> Calcium ion release –> activation of clotting cascade

36
Q

NAme an N.B. re alginates

A

Not for use in cavities –> FB reaction.

Need to be rinsed off with saline irrigation - used over wounds

37
Q

What is benefit of a fibrin haemostatic sealant

A

Independent of patients clotting ability

38
Q

What is Duraseal

A

A synthetic haemostatic sealant

–> 50% volume increase

39
Q

What is main concern re synthetic sealants?

A

Swelling

Coseal –> 400%

Duraseal –> 50%

40
Q

As fibrinolytics, how do lysine analogues compare with serine protease inhibitor?

A

Lysine analogues more potent

41
Q

How do anti-fibronolytics work?

A

Inhibit plasmin- or plasminogen mediated fibrinolysis

i.e. not effective if depletion of clotting factors or coagulopathy

42
Q

How is TXA excreted?

A

Unchanged in urine

43
Q

What is haemostatic effects of Desmopressin?

A

–> vWF and VIII release from endothelial cells

44
Q

What is ethamsylate

A

“salt” used as an oral or iv haemostatic agent

(falls under miscellaneous haemostatic products)

Interestingly may work synergistically with desmopressin and improves pancreatic blood flow in necrotizing pancreatitis + might be anti-inflammatory

45
Q

NAme 2 haemostatic polymers/minerals

A
  • Zeolite (exothermic) = crystalline mineral –> water adsorbtion + activates platelets + releases calcium (–> clotting cascade activation)
  • Chitosan: High SA – gel like clot. Independent of clottinh factors and still forms in presence of heparin/warfarin

2: Surgical Methods and Perioperative Care (11 decks)

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